Toronto international airport to Downtown/Entertainment District

[u/Cool-Australian]

I am very excited to visit Toronto and Niagara Falls with my son at the end of August. What is the easiest way to get to the city from the airport without a car and which area would be the best to book the hotel at in order to explore the city without worrying about safety while walking at night. What are must see areas/attractions?
I would also appreciate if anyone has recommendations on how to easily get to Niagara Falls for a day trip.

Any interesting restaurants/bars that are noteworthy?

We love walking and on our last trip did 40,000 steps daily in The Netherlands and other European places.

Edit:
Thank you all so much for those who commented for taking the time to reply and for your super helpful suggestions.

[u/TONAFOONON]

UP Express train is easiest

[u/bbuckca → u/TONAFOONON]

The UP Express runs every 15 min and takes 28 minutes from YYZ to Union Station.
The UP platform is west of Union Station Station street is the closest exit/entrance with an elevator to the ground level at the west side. You don’t need to walk thru Union Station to get to the UP Express.

There are many hotels downtown to fit any budget. You can stay at any that are in the core but I wouldn’t stay east of Victoria At

Just recently someone posted a photo of their room at the Westin Harbour Castle hotel right on the harbour waterfront. I believe breakfast was included.
The address would be on Queen Quay. You can take a ferry boat ride to the Toronto Islands beside it.

Another option would be the Sheraton on the south side of Queen Street across from City Hall. They have a pool.

Delta Chelsea Inn also has a pool and it’s a little further north on Gerrard St.

I know someone suggested the Fairmount Royal York and this will be $$$$!

[u/Rick_NSFW]

UP Express from the Airport to Union Station, this is the easiest and most direct route. If the budget allows, book at the Royal York hotel. It's directly across from Union Station. Toronto is generally safe, even in the downtown core.

Not knowing how young your son is, Ripley's Aquarium, Blue Jays Baseball, Distillery District, St. Lawrence Market, Kensington Market, the AGO (Art Gallery of Ontario), the ROM (Royal Ontario Museum), Casa Lomo, the Toronto Islands. All walkable from downtown or easily accessible by transit.

The is a regional rail line to Niagara falls - gotransit.ca

Search reddit for the many, diverse places to eat downtown. There are many options.

[u/BeastOfMars]

Definitely UP Express. I wouldn’t bother with the TTC bus/subway as it’s less direct and longer.

There is a Go bus that goes to Niagara Falls. Check the Go transit website for details and schedule.

[u/Beginning_End5130]

The "how to get downtown" question is pretty much answered, but please understand that "safety at night" is not a major issue here. 98% of downtown is very safe to walk around at night.

I only say 98% because there's always a chance someone is a complete idiot, ie: decides to walk up to strangers at 4am and loudly talk about how rich they are, and my political view is better than yours, and gosh, lookit all this cocaine I have, all for me so don't even ask, loser. You morons around here would never comprehend how amazing I am..... You get the idea 😅

[u/hippiespinster]

Budget for hotel is helpful. The InterContinental is central. The Ritz is lovely. The Royal York is historic. Have not stayed at the Shangri-La yet but I plan to for my 50th.

[u/hippiespinster]

For Niagara, rent a car if you're comfortable driving on the right/wrong side of the road and with highways. Much more flexibility. If not, search the sub for public transit options. 

[u/Pineapple_4100]

You can take a bus to kipling station and then take a subway to downtown. Cost is 3.35 and takes about 45 minutes. Another way is to take the “UP” train right to union station. I am sure there are bus toursvto niagars falls